A laminated glass in which two glass plates and an interlayer film for an automotive windshield containing a thermoplastic resin, such as plasticized polyvinyl butyral, are bonded to one another is widely used as an automotive windshield.
One method for producing such an automotive windshield is a vacuum deaeration method.
According to the vacuum deaeration method, a laminate including at least two glass plates with an interlayer film for an automotive windshield therebetween is put in a rubber bag. The laminate is vacuum suctioned, so that the laminate is preliminarily pressure-bonded while the air remaining between the glass plate and the interlayer film is removed. The laminate is then pressurized with heat, for example, in an autoclave to be fully pressure-bonded. Thus, an automotive windshield is obtained.
In the production of an automotive windshield, deaeration properties upon lamination of glass and the interlayer film for an automotive windshield are important. The interlayer film for an automotive windshield has minute projections and recesses on at least one surface thereof to ensure deaeration properties in the production of a laminated glass. In particular, when recesses among the projections and recesses have a groove shape with a continuous bottom (hereafter, also referred to as a “shape of an engraved line”) and such recesses in the shape of engraved lines are regularly formed to be adjacently arranged in parallel with one another, excellent deaeration properties can be exhibited (see Patent Literature 1, for example).
However, yield may be reduced when automotive windshields are produced by a vacuum deaeration method using such an interlayer film for an automotive windshield with recesses in the shape of engraved lines.